Voice mail systems allow multiple callers to leave messages in a called party's mailbox when the called party cannot answer a telephone call. Called parties are frequently unable to retrieve and delete messages from the mailbox as quickly as they are deposited, thus requiring voice mailboxes to have the ability to retain multiple messages. For example, calls to an ordering desk are rerouted to a voice mail system during peak calling periods, when all order takers are busy. Since called parties attach financial value to incoming calls, called parties frequently ask for voice mailboxes with enough message capacity to capture all incoming calls during a peak calling period, intending to retrieve the messages when incoming calling volume subsides. Retrieved messages are then deleted, making room for new messages. A typical large mailbox can store 60 minutes of messages, although larger mailboxes are becoming available.
A problem arises with current voice mail systems. Current systems use a mailbox "locking" system that allows each mailbox to be accessed by only a single individual at a time. Mailbox locking is necessary in conventional voice mail systems because conventional mailboxes can only play one message at a time. For example, a prior art voice mail system 100 is shown in FIG. 1. Callers 108a-z call in to voice mail system 100 through telephone network 104 and leave messages in one or more mailboxes 102a-z. Multiple callers may simultaneously leave messages in a single mailbox, such as 102a. However, prior art systems allow only one user at a time to retrieve a message from mailbox 102a because each mailbox can only play one message at a time.
A called party accesses a mailbox by dialing into the voice mail system, either directly, in the case of an in-house system, or through the telephone network, in the case of centralized network systems. The user then supplies a mailbox number and password. The user then gets exclusive access to the mailbox--the mailbox cannot be accessed by anyone else while the user is accessing the mailbox. In addition to only allowing one user access, only one message can be played to that one user at a time. Thus, messages must be retrieved sequentially in time, overlapping or concurrent retrieval is not possible. As a result, company that uses a voice mail system to capture calls during peak calling periods can employ only one employee to retrieve messages during slow periods, even if multiple employees are available to retrieve messages. This has a negative impact on productivity. Furthermore, the user retrieving the messages must listen to all of the messages sequentially, so it takes the user one hour to listen to 60 one minute messages, even if the messages were deposited over a very short time interval. Although some systems allow high priority messages to be presented to the called party first, this merely changes the order of the sequence, not its length. The length of time to retrieve and delete messages keeps a user busy for a long period of time, and creates the chance that the mailbox will still have messages in it when a new peak calling period begins. The situation is exacerbated by improvements in storage technology which will make it possible to create mailboxes with many hours of message storage. A need arises for a voice mail system in which multiple messages can be retrieved from a single mailbox at the same time.